Currently under investigation are the following projects: (1) Characterization of the Streptococcus mutans LM-7 plasmid. It has been found that the LM-7 strain gives rise to glucosyltransferase (GT) negative mutants at relatively high frequency. However, when these mutants were examined, they were found to contain plasmid DNA with the same molecular weight as the parent. The possibility that the plasmid controls GT, but that this function is readily lost is being studied. (2) Characterization of the GT elaborated by S. mutans C67-1. It has been found that this GT has an apparent molecular weight (by gel filtration) greater than 15 million. Several detergents were able to dissociate the GT aggregate into lower molecular weight species. These species are currently being characterized. BIBLIOGRAPHIC REFERENCES: Chassy, B.M., Beall, J.R., Bielawski, R.M., Porter, E.V. and Donkersloot, J.A.: Occurrence and distribution of sucrose-metabolizing enzymes in oral streptococci. Inf. Immun. 14: 408-415, 1976. Wittenberger, C.L., Beaman, A.J., Lee, L.N., McCabe, R.M. and Donkersloot, J.A.: Possible role of Streptococcus salivarius glucosyltransferase in adherance of Veillonella to smooth surfaces. In Schlessinger, D., (Ed.) Microbiology 1977, 417-421, 1977.